Flush toilets for discharging waste by flushing with flush water supplied from a flush water source have for some time been known in which, as noted in Patent Document 1 (WO 2004/022862), for example, a spout portion for spouting flush water into a bowl to form a circulating flow is positioned close to a position on one side of the bowl centered on the front-rear direction thereof, at which there is a change from a small curvature to a large curvature, as seen in plan view.
In such conventional flush toilets, measures were taken such as providing overhang portions to prevent the circulating flow from splashing out in areas in which the bowl curvature changes dramatically (curved portions).
However, in the conventional flush toilet of the above-described Patent Document 1, when flush water spouted from a spout water portion circulates over a curved portion, the problem arises that sudden changes in centrifugal force acting on flush water can occur even if splashing is suppressed by an overhang portion.
Thus there is a risk that flush water circulation efficiency will be degraded, and a risk that the bowl cannot be sufficiently flushed.
In particular, the problem is especially pronounced in rims in which the overhang portion is shallow in the depth direction, or which have a shape which does not include an overhang portion.
The present invention was therefore undertaken to solve the above-described problems with the conventional art, and has the object of providing a flush toilet with which the occurrence of sudden changes in centrifugal force acting on flush water can be effectively suppressed when flush water spouted from a spout port on a rim spouting portion circulates along a curved portion, and flushing efficiency in the bowl can thus be improved.
To accomplish the above-described object, the present invention is a flush toilet for discharging waste with flush water supplied from a flush water source, the flush toilet comprising: a bowl including a bowl-shaped waste receiving surface and a rim formed at a top edge of the waste receiving surface; a discharge path connected at a bottom of the bowl to discharge waste; a rim spout portion disposed on the rim, the rim spout portion being configured to spout flush water into the bowl so as to form a circulating flow; and a water conduit configured to supply the flush water to the rim spout portion; wherein a flow path on a downstream side of a spout port on the rim spouting portion forms a curved portion, a curvature of the curved portion being configured to change from small to large in at least a position within an inner circumferential wall of the rim, the position being closest to the spout port, and the curved portion is formed by a transition curve as seen in plan view.
According to the invention thus constituted, a curved portion in which the curvature changes from small to large is formed in at least the position closes to the rim spout port of the rim inner circumferential wall, and this curved portion is formed by a transition curve as seen in plan view; by so doing, the occurrence of sudden changes in centrifugal force acting on flush water can be effectively suppressed when flush water spouted from the rim spouting portion spout port circulates along the curved portion, therefore flushing efficiency in the bowl can be improved.